1. Field of the Invention
The present invention relates to a washing machine, and more particularly, to a method of performing a spinning operation for a washing machine.
2. Discussion of the Related Art
Generally, a washing machine performs washing by executing a washing operation, a rinsing operation, and a spinning operation. The spinning operation includes a load pre-balancing cycle, a load weighing cycle, a load balancing cycle, and a main spinning cycle.
According to the principles of the related art, before the main spinning cycle, a microprocessor determines a load weight of wet clothes to measure spinning operation parameters, which helps to balance the load in the tub. However, it is very likely that some wet clothes in the washing machine become tangled one another by a nature of the mechanism of a drum washing machine. Consequently, an unevenly distributed load of the clothes in the washing machine creates an unnecessary moment about the center of a tub, which makes the motor irregularly rotate. For example, when a chunk of the wet clothes spins from a top to a bottom of the tub in the washing machine, the moment created by a gravity of the chunk forcibly rotates the motor over its limit. On the other hand, when the chunk spins from the bottom to the top, it creates an opposite rotational force that prevents the motor from rotating in the right direction. Therefore, the entanglement of the clothes causes a vibration of the tub, a nose, and a walking of the washing machine, all of which resulted in inaccuracy of the load weight of the wet clothes. As a result, the inaccurate load weight causes the inaccurate spinning operation parameters, which influence a performance of the main spinning operation.
According to the principles of the related art, after the load weighing cycle, the rotational speeds up the tub with a constant acceleration regardless of the load weight to perform the load balancing cycle. Speeding with the constant acceleration has caused a problem of the vibration of the tub, the walking of the washing machine, and the poor performance of the main spinning cycle. For example, if 10 kg clothes are not evenly distributed and a relatively low speed is used to redistribute them, it will be very difficult for the relatively low speed to not only balance the 10 kg load evenly but also reach a desired speed quickly. So to speak, the 10 kg unbalanced load creates the moment about the center of the tub. The moment then causes the vibration of the motor, the noise, the walking of the washing machine, and a lagging of the cycle. Thus, the load balancing cycle needs to last longer, meaning that more power is needed and inefficiency of the spinning operation is occurred.
During the load balancing cycle, the microprocessor determines an unbalancing value, which represents how irregularly the load of the wet clothes is distributed in the washing machine. Even though the microprocessor determines whether the main spinning operation can be carried out dependent upon the unbalancing value, the load is not likely to be evenly balanced for the smooth performance of the main spinning cycle because the unbalanced distribution levels are determined below a resonance frequency range. It is realized that the unbalanced distribution levels alter prominently within the resonance frequency range. Therefore, the unbalance load determined below the resonance frequency range is not accurate, which influences the performance of the main spinning cycle.